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analyzer: add sm-fd.dot

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Add a .dot file to document the file descriptor state machine.

gcc/analyzer/ChangeLog:
	* sm-fd.dot: New file.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>
This commit is contained in:
David Malcolm 2022-10-26 16:44:23 -04:00
parent f7d2881817
commit 593254ae03
1 changed files with 109 additions and 0 deletions
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109
gcc/analyzer/sm-fd.dot Normal file
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/* An overview of the state machine from sm-fd.cc.
Copyright (C) 2022 Free Software Foundation, Inc.
Contributed by David Malcolm <dmalcolm@redhat.com>.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
/* Keep this in-sync with sm-dot.cc */
digraph "fd" {
/* STATES. */
/* Start state. */
start;
/* States representing a file descriptor that hasn't yet been
checked for validity after opening, for three different
access modes. */
unchecked_read_write;
unchecked_read_only;
unchecked_write_only;
/* States for representing a file descriptor that is known to be valid (>=
0), for three different access modes. */
valid_read_write;
valid_read_only;
valid_write_only;
/* State for a file descriptor that is known to be invalid (< 0). */
invalid;
/* State for a file descriptor that has been closed. */
closed;
/* State for a file descriptor that we do not want to track anymore . */
stop;
/* TRANSITIONS. */
/* On "open". */
start -> unchecked_read_only [label="on 'X = open(..., O_RDONLY);'"];
start -> unchecked_write_only [label="on 'X = open(..., O_WRONLY);'"];
start -> unchecked_read_write [label="on 'X = open(..., ...);'"];
/* On "creat". */
start -> unchecked_write_only [label="on 'X = create(...);'"];
/* On "close". */
start -> closed [label="on 'close(X);'"];
unchecked_read_write -> closed [label="on 'close(X);'"];
unchecked_read_only -> closed [label="on 'close(X);'"];
unchecked_write_only -> closed [label="on 'close(X);'"];
valid_read_write -> closed [label="on 'close(X);'"];
valid_read_only -> closed [label="on 'close(X);'"];
valid_write_only -> closed [label="on 'close(X);'"];
constant_fd -> closed [label="on 'close(X);'"];
closed -> stop [label="on 'close(X);':\nWarn('double close')"];
/* On "read". */
closed -> closed [label="on 'read(X);':\nWarn('use after close')"];
unchecked_read_write -> unchecked_read_write [label="on 'read(X);:\nWarn('use without check')'"];
unchecked_read_only -> unchecked_read_only [label="on 'read(X);:\nWarn('use without check')'"];
unchecked_write_only -> unchecked_write_only [label="on 'read(X);:\nWarn('use without check')'"];
valid_write_only -> valid_write_only [label="on 'read(X);:\nWarn('access mode mismatch')'"];
/* On "write". */
closed -> closed [label="on 'write(X);':\nWarn('use after close')"];
unchecked_read_write -> unchecked_read_write [label="on 'write(X);:\nWarn('use without check')'"];
unchecked_read_only -> unchecked_read_only [label="on 'write(X);:\nWarn('use without check')'"];
unchecked_write_only -> unchecked_write_only [label="on 'write(X);:\nWarn('use without check')'"];
valid_read_only -> valid_read_only [label="on 'write(X);:\nWarn('access mode mismatch')'"];
/* On "dup". */
closed -> closed [label="on 'dup(X);':\nWarn('use after close')"];
/* plus stuff for the new fd. */
/* On "pipe". */
start -> valid_read_write [label="when 'pipe()' succeeds"];
/* on_condition. */
unchecked_read_write -> valid_read_write [label="on 'X >= 0'"];
unchecked_read_only -> valid_read_only [label="on 'X >= 0'"];
unchecked_write_only -> valid_write_only [label="on 'X >= 0'"];
unchecked_read_write -> invalid [label="on 'X < 0'"];
unchecked_read_only -> invalid [label="on 'X < 0'"];
unchecked_write_only -> invalid [label="on 'X < 0'"];
/* Leaks. */
unchecked_read_write -> stop [label="on leak:\nWarn('leak')"];
unchecked_read_only -> stop [label="on leak:\nWarn('leak')"];
unchecked_write_only -> stop [label="on leak:\nWarn('leak')"];
valid_read_write -> stop [label="on leak:\nWarn('leak')"];
valid_read_only -> stop [label="on leak:\nWarn('leak')"];
valid_write_only -> stop [label="on leak:\nWarn('leak')"];
}